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Diamond Processing Track Record

Re-treating diamond-bearing dumps

As part of the new partnership model introduced at the start of the year, De Beers has involved BATEMAN
in a number of projects to recover diamonds from tailings dumps at its older mines.

These dumps contain reject material deposited over many years when the diamond-recovery processes were
not as efficient as they are today and are now known to contain meaningful amounts of small diamonds.
The possibility, however, of finding larger stones too is not excluded.

James Nieuwenhuys, BATEMAN General Manager, Diamonds, reveals that studies are being conducted on
about a dozen different diamond-recovery routes which could be applied to the reprocessing of dumps, the
objective being to have available a suite of processes applicable to all kinds of dump materials and to
contain dump-reprocessing costs to an absolute minimum.

In respect of milling, the partnership will be exploring a combination of Western and Russian technologies,
arising out of testwork undertaken by BATEMAN a few years ago in Siberia for a large diamond exploration,
mining and marketing company in the Russian Federation.

The key to the milling technology is the slow mill speed which minimises diamond breakage. As many
dumps are in arid locations, water usage will also have to be minimised. BATEMAN has entered into
agreements with suppliers of novel milling technology, such as cantilever and planetary systems and
innovative liners, so these can be evaluated for use in dump reprocessing.

Some of the novel technology is already finding application in current projects BATEMAN is undertaking
with De Beers. At Namdeb's E-Bay diamond-liberation project in Namibia, the wet-crushing system being
installed is the first of its kind in the De Beers Group and enables the plant to treat all potentially viable
deposits including clay-rich and very hard cemented materials.

Because of the remote location of many of the dumps and the potential need to relocate the equipment from
time to time to other nearby dumps, BATEMAN is drawing heavily upon its experience with modular-
processing plants which will be applied to all the major processes needed for diamond recovery, e.g.
crushing, milling, dense-media separation, X-ray recovery, etc.

According to Nieuwenhuys, several factors motivate projects to re-treat old dumps. "There is today a greatly
improved understanding of diamond-liberation processes and more effective methods to recover the
diamonds are available," says Nieuwenhuys. "At the same time, the kimberlite in the old dumps has
weathered extensively during years of exposure to the elements, facilitating the release of any diamonds
associated with the kimberlite. Also, the availability of high-quality primary resources is decreasing and
diamond producers are on the lookout for additional resources."

"All old diamond mines have such dumps and this includes all the mines in South Africa, Botswana and
Namibia," says Nieuwenhuys.

"In South Africa, the newly promulgated Mining Charter, which fosters a 'use-it-or-lose-it' approach to the
exploitation of mining resources, is making mining companies take a far more careful look at smaller
deposits. Accordingly, BATEMAN is in discussion with several black economic-empowerment companies
aimed at providing the technology and backup required to get these ventures started.

"Further afield, the improving political situation in the Democratic Republic of the Congo (DRC) and Angola is
also opening up possibilities there. Sampling programmes in Canada, for which BATEMAN equipment has
been purchased in recent years, are also revealing promising recovery ventures."

Largest to-date DMS diamond-processing module for Miba

The new 200 t/h dense-media separation (DMS) module to be delivered to Miba in Mbuji Mayi in the
Democratic Republic of the Congo (DRC) will be the largest diamond-processing module supplied by
BATEMAN to date. It is an upgrade of BATEMAN's standard 150 t/h unit, which is now well proven in the
industry, six having been supplied since the first one was delivered in 1998.

The new module will form part of Miba's 400 t/h NLK2 kimberlite-treatment plant and is in effect a repeat order.
Miba's NLK1 diamond-processing facility was supplied by BATEMAN in 1998.

The BATEMAN policy of continuous improvement to the design of its modular plants by incorporating feedback
from experience in the field was again applied in this project. As a result several new features have been
designed into the new model to enhance its performance.

The new layout facilitates ease of maintenance and operation. The incorporation of four 420 mm diameter
cyclones improves the recovery efficiency of smaller diamonds, the carefully chosen screens enhance
processing efficiency and design changes in the magnetic separation system facilitate recovery of the
ferrosilicon heavy medium used in the DMS circuit.

The processing circuit of the NLK2 module comprises feed-preparation screens, mixing boxes, cyclone
feed pumps, float and sink screens and combined collection sumps for the heavy and dilute media.
Besides the cyclones which separate the diamonds, care has been taken to ensure the correct media
densification using tube densifiers. The magnetic separators recover the ferrosilicon from the dilute medium.
The plant is equipped with all the required pumps, screens, piping and control circuits.

The total weight of the plant, which comprises 10 modules, is 130t. Before transport to site, it will be trial
erected at the factory and fully tested. It will then be disassembled and transported to the mine. The first
part of the trip to the mine's railway siding at Mwene-ditu in the DRC will be handled by Spoornet, the South
African rail utility, for which about 90 DZ rail wagons in total will be needed to carry the whole consignment.
Then road transport will be utilised by Miba for the remaining 100 km to the mine.

EBay project featured on Namibian TV

The Namibian Broadcasting Corporation featured a special screening of Namdeb's Elizabeth Bay
(EBay) Liberation Project near Lüderitz to showcase the country's potential to investors. The Elizabeth
Bay mine is an important part of Namibia's economy as it contributes 8 % of the country's annual
diamond output.

While the project will triple the mine's diamond output for the next three years and extend its life by 10 years,
it will also enhance the sustainability of Lüderitz by providing continued employment to over 200 inhabitants
of this small coastal town.

BATEMAN's role in the N$400M (about US$50M) upgrade of the treatment plant at the mine includes
engineering, designing, procuring and constructing the crushing, screening and milling circuits. The work
started in November 2002 and at the end of 2003 progress was on schedule, with the design of the plant
being complete and 70 % of the civil and 30 % of the structural work having been done. Electrical installation
is due to commence early in 2004 and it is estimated the plant will be completed by the end of July 2004.

The complement of construction workers at the site, more than 80 % of which are local Namibians, has now
peaked at 550 workers, and an excellent safety record has been maintained, with one lost time injury being
incurred during the 418 333 manhours worked to the end of 2003.

A highlight of the project thus far is the good client-contractor relationship which is in operation on the project.
This project has been serving as the prototype for De Beers' innovative partnering concept which it is
envisaged will become a model for future projects. The success on the EBay project is endorsing the
validity of a cooperative rather than the traditional confrontational approach between client and contractor
in the conduct of large projects.

Modular diamond plant for Tanzania

BATEMAN has supplied a complete 30 t/h alluvial treatment plant to El Hillal Minerals – the first modular
diamond processing plant it has provided to a Tanzanian operation. The plant includes a 30 t/h run-of-mine
front-end module, a 20 t/h dense medium separation (DMS) module and a containerised x-ray recovery
plant, plus all associated conveyors and equipment.

The front end of the plant, which receives the feed of alluvial ore, comprises a static grizzly, a BATEMAN
vibrating feeder, a scrubber and a surge bin. The 20 t/h DMS module, a standard modular plant designed
and supplied by BATEMAN, processes diamond containing gravel ranging from +2 mm to -25 mm at a
rate of 20 to 25 t/h. The concentrated material is pumped to the recovery plant which consists of a
concentrates-classifying screen, housed in a secured, caged enclosure, which feeds the wet x-ray
recovery machine via a tube feeder. The entire recovery plant is completely hands-off and sorting is
done in the fully-equipped, containerised unit.

El Hillal’s mine is situated adjacent to the famous Williamson Mine in the Shinyanga region of Tanzania;
the site is approximately two hours drive from the port of Mwanza on the shores of Lake Victoria. The entire
plant was transported from South Africa by road using eight tri-axle flat-bed trucks. Travelling through
Zimbabwe and Zambia, often over almost impassable stretches of road, the convoy reached its final
destination in Tanzania in 13 days. At the site, the entire plant was erected within one month under
BATEMAN supervision.

Diamond process plant for Russia’s Perm region

BATEMAN has supplied a modular diamond sampling plant to JSC "Permgeologodobycha", a newly-
formed company established specifically for geological prospecting, discovery and exploitation of
alluvial diamond deposits in the Perm Region of Russia. JSC "Permgeologodobycha" is located in the
town of Krasnovishersk in Perm and is a subsidiary of JSC "Uralkaly" - one of the world’s largest
producers of potassium fertiliser.

The plant will be used to process diamondiferous alluvial material with the objective of determining
diamond grade efficiently using state-of-the-art dense-media separation (DMS) technology. The
contract, worth in excess of US$300 000, commenced in January 2003 and was completed at the
end of June 2003. BATEMAN was responsible for equipment supply, commissioning, and personnel
training. In order to meet the tight deadline, which required delivery of the equipment to the site within
four months of the contract being signed, the plant had to be air-freighted from Johannesburg to Europe
and then taken by road over a distance of some 6 000 km to Krasnovishersk.

The equipment supplied included a 5 t/h DMS modular plant and a 1,5 m diameter by 3 m scrubber.
As nonnuclear sources are preferred in Russia for diamond sorting, the DMS plant was designed with
an appropriate density controller.

Since BATEMAN’s modular process plants are pre-tested at the factory and delivered in modular form,
they require minimal civil construction on site, making them ideally suited for remote locations such as
Krasnovishersk, where skilled labour and a sophisticated infrastructure are not readily available. In
addition, tickborne encephalitis poses a serious health threat in this region.

The contract for the diamond sampling plant was signed within only four months of the date of the first
client meeting, which, says James Nieuwenhuys, BATEMAN General Manager, Diamonds, was due
not only to its standing as a world leader in engineering diamond process plants, but also to its
knowledge and experience of working in different countries and across different cultures.

Increasing Venetia Mine’s ROM production

BATEMAN has modified sections of the existing plant at the Venetia Mine 80 km west of Messina,
RSA, to increase the throughput of run-of-mine (ROM) ore from 4,5M to 5,9M t/yr.

The project arose out of an in-house study by Venetia that revealed the feasibility of increasing the plant
throughput, providing appropriate modifications were made. The mine’s process engineers developed
the conceptual flow sheet.

BATEMAN prepared a technical and cost-estimate proposal to implement the modifications and was
awarded a R10,8M reimbursable contract on condition that several requirements could be met.
As much as possible of the existing installation would have to be re-used and the existing plant’s high
standard of access and maintenance would have to be maintained. There would have to be minimal
impact on current mine production and BATEMAN’s involvement in the project would have to be completed
within five months, with hot commissioning commencing early in March 2003.

Safety was to be a critical and high- priority factor at all stages of construction and commissioning,
particularly as the modifications were to be executed in an operating plant with a very good safety record.

The project involved exchanging the existing secondary crusher’s dewatering screens and associated
underpans and chutes with double-deck screens, to enable the feed from the crushers to be separated
into coarse and fine streams. In addition a dewatering screen was introduced below the new re-crush
crusher which discharges onto a modified conveyor. The fine-material stream now bypasses the
secondary scrubbers, effectively providing additional capacity.

So the fine material could be sent to the discharge hoppers of the scrubbers, an existing conveyor was
extended and re-aligned with the drive being repositioned in the refurbished building. A new conveyor
was installed and the scrubber building modified extensively.

The project was completed on time and as per the client’s specifications. The BATEMAN project team
also maintained an exemplary safety record and during the 9 664 man hours worked on site, no lost-time
accidents were incurred.

BATEMAN plant for Sierra Leone diamond industry

BATEMAN recently welcomed a high-level governmental delegation from Sierra Leone to its Boksburg
campus where they viewed the company’s engineering capabilities and facilities. The delegation
comprised the Minister of Mineral Resources, Minister MS Deen, the Deputy Director of Mines,
Mr UB Kamara, and Mr Sadig Silla of Branch Energy, a Sierra Leone diamond mining concern. They
were being hosted in Johannesburg by Magma Resources, shareholders in a project BATEMAN is
carrying out for Koidu Diamond Mine in Sierra Leone.

The visit to BATEMAN reflects the keen interest the government of Sierra Leone has in revitalising its
diamond mining industry since it was destroyed in the civil war, and, we believe, the sound working
relationship BATEMAN is establishing with mining ventures in that country,” says Louis Nell, BATEMAN
Engineering Manager, Modular Plants.

BATEMAN is currently shipping a modular process plant, under contract to Diamond Works, RSA, for
commissioning in mid 2003 at Koidu mine in central east Sierra Leone. The plant handles 50 t/h run-of-mine
ore which will be fed to the process plant for crushing, scrubbing, screening, dense-media separation
(DMS) and X-ray recovery of diamonds.

The plant offers several advantages for Koidu mine. As a typical BATEMAN modular plant designed to
survive harsh African conditions, sections of the plant

are built, erected and tested in the factory in South Africa to minimise remedial work on site. It also requires
minimal civil construction. This is of particular benefit to remote sites, such as Koidu, where skilled labour
and a sophisticated infrastructure are not readily available.

The two kimberlite pipes mined by Koidu mine are reported to be a source of very large, high quality diamonds.
A unique feature of the BATEMAN modular process plants is that an X-ray separation facility is built into the
process which enables the large diamonds to be captured before the ore enters the secondary crushing and
DMS phases where they could be damaged.

The new plant was constructed using as much as possible of a previous plant that was built by BATEMAN for
the same mining operation, but never commissioned as it had been severely damaged during the civil war.

Modular DMS kimberlite process plant for Damtshaa

A modular dense-media separation (DMS) plant to process kimberlite, which has been delivered to the
Damtshaa mine, forms part of a BATEMAN project to establish a diamond-processing plant and its
associated infrastructure for Debswana at the mine about 17 km east of Orapa in northern Botswana.

The processing plant, rated at 200 t/h, has primary- and secondary crushing, integrated DMS, load-out
and waste-disposal circuits. It will process a feed of kimberlite from the BK pipes in the area to produce
a diamond concentrate which will be transported by road for final treatment at the main recovery facility
at Orapa.

The integrated DMS plant comprises a 150 t/h primary circuit feeding a 50 t/h reconcentration circuit.
These circuits have a common dense-medium supply circuit, the first of its type to be provided by
BATEMAN. The diamond concentrate is stored in a 50 t load-out facility, fully automated to deposit
batches of the concentrate into truck-mounted flasks for transportation to Orapa.

This is the fifth modular DMS plant with a capacity of 150 t/h to be designed and manufactured by BATEMAN
in the past three years. With 120 t of steelwork and 95 t of platework, it is also the largest plant of this type
to have been supplied by BATEMAN. The top floor of the load-out structure is 23 m off the ground and two
mobile cranes, one of 20 t and the other of 18 t, were required for the trial erection of the plant at the
workshop near Johannesburg. It was then dismantled into sections small enough to be conveyed by
15 Superlink road-haul trucks to the Orapa mine about 810 km away.

The order for the modular DMS plant was placed in June 2001 with trial erection at the factory being
completed in March 2002. Dismantling and transport to site required two-and-a-half weeks and on
site re-erection and installation of the housing six and four weeks respectively.

Exploration successes with a BATEMAN DMS plant!

A year ago BATEMAN supplied one of its 1 t/h transportable modular dense-media separation plants to
Lakefield Research Limited, Ontario, Canada. In the June 2001 issue of the newsletter Lakefield Research
Highlights, the plant is accorded a glowing recommendation. BATEMAN Globe reprints an extract from the
Lakefield newsletter:

“New DMS plant sparkles

The success of Ekati, Canada’s first diamond mine, has spurred exploration for more deposits across the
country. To meet the explorers’ requirements, Lakefield Research in Ontario enhanced its diamond
processing capabilities with the acquisition of a dense media separation (DMS) plant last year. The
plant has a nominal 1 ton per hour processing rate, ideal for handling bulk samples from late stage
exploration projects.

This facility is the only independent, commercial fee-for- service pilot scale DMS plant in the Americas,
and perhaps in the world.

Twin Mining Corp. of Toronto, was the first client to use the plant. A 350 tonne sample was delivered by
helicopter, barge and truck to Lakefield from Twin Mining’s property in the Torngat mountains in northern
Quebec. The kimberlite was crushed to a nominal - 6 mm, then scrubbed to break up any clay-like
aggregates and to remove the fines (minus 1 mm material). The diamonds were concentrated into a
heavy mineral fraction in the DMS plant and recovered using a grease table. A diamond recovery rate
of 99.5 % was achieved.

North American diamond explorers can use this DMS plant at Lakefield Research to quickly process
bulk samples, while being confident that they will receive high quality, secure and confidential results. ”

 

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